There seem to be about as many answers to this as there are members here; everybody has their favorite way to book. About the only thing everybody agrees on is that cruise prices change--frequently.
My advice to you would be, since this will only be your second cruise, stick with your travel agent since you seem pleased with them. You might save a few bucks doing it yourself, but until you have a few more cruises under your belt, you could also really trip yourself up--costing you more in the long run.
When you are a little more seasoned you can try it yourself; but there is a lot to be said for having a relationship with an agent that knows your likes and dislikes. And they can sometimes get perks for you that you couldn't get yourself.
Good luck and happy cruising!

I absolutely swear by Ann Hayward at Cruise Vacation Center.com out of Yonkers, New York. I gave her so many headaches when we booked 11 people on the Alaskan Inside Passage in 7/2005, but she was sooooo professional and took my awkward position (booking for some of the travelers from hell, and I don't mean Hell, Grand Cayman) into consideration...she was great and she did great by us.

As far as i understand, the cruise line sets the price for a particular cruise. So there is a level playing field. If some agency does deep discounts they are flagged.
I would always go with a TA. In the event something is wrong - do you want to talk to a website or someone that knows what they are doing?
I checked with cruisecompete for my last cuise just for info and i got 5 quotes all within 20$.

We booked our cruise with Vacations To Go! Louis Hardy lhardy@vacationstogo.com is our TA and is very patient and nice (I had MANY questions for him and he never seemed irritated!) He is also very friendly and does not come off as trying to get a huge commission! I hope that helps!
Christie